Signalling arrangement for telecommunication systems



A ril 29, 1958 R. M. M. OBERMAN 2,

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SIGNALLING ARRANGEMENT F OR TELECOMMUNICATIQN SYSTEMS Filed June 4, 19521:5 Sheets-Sheet i INVENTOR: Roch) M- Oberman April 29, 1 958 R. M. M.OBERMAN SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June4, 1952 13 Sheets-Sheet 3 EXCHANGE A April 29, 1958 R. M. M. OBERMAN2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 4 Flt-14 mums: A

\NVENTORI Roe'Of MM. Ober mfl BY: flmxue jinx April 29, 1958 OBERMAN2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 5 Hi5 EXCHANGE A INVENTORZ Roei f M.M-O l ermar BAMI/11404 April 1958 R. M. M. OBERMAN' 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 6 H16 EXCHANGE 8 INVENTOR.

Roel f M' Obel'mq r.- Mad/M A ril 29, 1958 R M. M. OBERMAN 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 7 EXCHANGE C April 29, 1953 R. M. M. OBERMAN 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 8 7 EXCHANGE c FlfiB INVENTOR. Roe f Oberman Br: 7,;owl/lulu R. M. M. OBERMAN April 29, 1958 SIGNALLING ARRANGEMENT FORTELECOMMUN ICATION SYSTEMS Filed June 4, 1952 13 Sheets-Sheet 9 JPL I NVEN TOR;

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April 29, 1958 R. M. M. OBERMAN 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 10 FIG. 10

EXCHANGE B INVENTOR Roelof I LM' Qberman 8Y= wane MM April 29, 1958 R.M. M. OBERMAN 2,332,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet ll PHI EXCHANGE D Flfi.

April 29, 1958 R. M. M. OBERMAN 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 12 77m 19 2o d J I JL III?

A FHHI' C LJ lNVENTOR R [0? M, M Oberman By: y wulz 1M April 29, 1958 R.M. M. OBERMAN 2,832,834

SIGNALLING ARRANGEMENT FOR TELECOMMUNICATION SYSTEMS Filed June 4, 195213 Sheets-Sheet 13 INVENTOR RoeloF M.M- Oberm n B wad/J. M a

United States Patent SIGNALLING ARRANGEMENT FOR TELE- COMMUNICATIONSYSTEMS Roelof M. M. Oberman, The Hague, Netherlands, assignor to DeStaat der Nederlanden, Ten Deze Vertegenwoordigd Door deDirecteur-Generaal der Posterijen, Telegrafie en Telefonie, The Hague,Netherlands Application June 4, 1952, Serial No. 291,613 In NetherlandsApril 26, 1941 Section 1, Public Law 690, August 8, 1946 Patent expiresApril 26, 1961 23 Claims. (Cl. 179-18) The present invention relates toautomatic signalling systems, in particular to systems in whichregisters are used, which control the various switching operations bymeans of voice or audio-frequency currents.

This application is a continuation-in-part of the copending applicationSerial No. 772,870, filed September 8, 1947, for Automatic Telegraph orTelephone System for Telemetering or Telecontrol.

It is an object of the present invention to control the local or trunkswitching means by means of audio-frequency currents.

It is another object of the present invention to provide a system inwhich all facilities of registers may be used.

It is a further object of the present invention to provide the systemwith a frequency test controlling the position of the local and trunkswitching means.

It is still another object of the present invention to identify thecalling subscriber by means of a frequency test.

A signalling arrangement comprises in its broadest aspect a plurality ofgenerators each producing an alternating current having a frequencydifferent from the fre quency of the alternating currents produced bythe other of the generators; a first set of band filters each connectedin circuit with one of the generators and passing the alternatingcurrent frequency produced by the generator to which it is connected incircuit, a second set of band filters each connected in circuit with thegenerators and passing the alternating current frequency produced by thegenerator to which it is connected in circuit, a first switch meanshaving a first bank of contacts connected, respectively, to the firstband filters, a second switch means having a second bank of contactsconnected, respectively, to the second band filters, a first wiperbrushing the first bank of contacts, a second wiper brushing the secondbank of contacts, a connection between the first and second wipers,current-responsive means inserted in the connection, electromagneticmeans for moving one of the wipers over the bank of contacts cooperatingwith the same, and means controlled by the current-responsive means forenergizing the electromagnetic means when the current-responsive meansdoes not respond to any current, whereby the electromagnetic means isput out of action when the wipers contact, respectively, contacts of thebanks connected to the band filters.

An embodiment of the present invention comprises a first station sendinga current impulse, a second station to be connected with the firststation, register means, a plurality of voice frequency generatorsforming part of the register means, each of the generators producing analternating current having a frequency different from the frequencies ofthe alternating currents produced by the other of the generators,marking switch means forming part of the register means, the markingswitch means having a bank of contacts connected, respectively, to thegenerators so that the contacts of the bank of said marl ing switchmeans are marked, respectively, by the fre quencies of the alternatingcurrents produced by th generators, the frequency of any of the contactsof th bank of the marking switch means being diiferent fror any of thefrequencies of the other contacts of the ban of the marking switchmeans, a wiper forming part of th marking switch means and cooperatingwith the bank c contacts of the marking switch means, means for pos:tioning the wiper of the marking switch means by th current impulse sentby the first station, selector switc means for making a connectionbetween the first statio and the second station, the selector switchmeans havin a bank of contacts connected, respectively, to the generators so that the contacts of the bank of the selector switc means aremarked, respectively, by the frequencies of th alternating currentsproduced by the generators, the fre quency of any of the contacts of thebank of the seler tor switch means being different from any of the frequencies of the other contacts of the contact bank of th selector switchmeans, the frequencies of the contacts c the bank of the selector switchmeans being equal, resper tively, to the frequencies of the contacts ofthe bank c said marking switch means, a wiper forming part of thselector switch means and cooperating with the ban of contacts of theselector switch means, an electric Cll cuit, an electro-magnet having awinding arranged in th electric circuit, the electromagnet stepping thewiper o the selector switch means along the bank of contacts 0 theselector switch means, and means for interruptin the electric circuitand thereby de-energizing the windin of the electromagnet when thewipers contact, respective ly, contacts of the banks of the marking andselecto switch means being marked by equal frequencies so a to stop thewiper of the selector switch means, thereb positioning the selectorswitch means according to th current impulse sent by the first stationso that the se lector switch means connect the first station and the second station with each other.

Preferably a contact is arranged in the electric circui in series withthe winding of the electromagnet and mean are provided for opening theelectric contact so as to de energize the winding of the electromagnetwhen the wiper contact, respectively, contacts of the banks of themarkin and selector switch means being marked by equal fre quencies.

Preferably a relay controls the electric contact so a to open the samewhen the relay is energized, and a se of rectifiers has input terminalsconnected, respectively, '[t the wipers of the marking and selectorswitch means the output of the set of rectifiers being connected to thlrelay.

Preferably means are provided for preventing the ener gization of therelay when the second station is busy The novel features which areconsidered as character istic for the invention are set forth inparticular in th appended claims. The invention itself, however, botl asto its construction and its method of operation, to gether withadditional objects and advantages thereof will be best understood fromthe following descriptioi of specific embodiments when read inconnection witl the accompanying drawings, in which:

Fig. 1 is a circuit diagram of an embodiment of th: invention having apositioning and identifying register Figs. 1a, 1b, and 1c are diagramsshowing three dif ferent ways of combining the circuit diagrams shown itFigs. 3 to 12;

Fig. 2 shows a decimal automatic exchange with a posi tioning andidentifying register according to the invention Figs. 3 and 4 showtogether, as indicated in Fig. 1a the arrangement of a three digittelegraph or telephone system according to the invention;

Figs. 3, 5, 6, 7 and 8 taken together as indicated in Fig. 1b, show anembodiment of a trunk telegraph or tele phone system according to theinvention;

Figs. 3, 5, 9, l0, 7, 8, 11 and 12 taken together as indicated in Fig.1c show an embodiment of a trunk routing system according to theinvention; and

Fig. 13 shows an embodiment of a local trunk group finder according tothe invention.

Fig. 1 shows the principle of the invention in an arrangement of anautomatic exchange associated with e. g. four subscribers. Having liftedhis book the calling subscriber P receives in a conventional way dialingtone indicating that over the call finder OZ a free cord DS has beenseized to which a free register is connected over a register finder RZ.The number wanted by the calling subscriber consisting in this exampleof one digit, is registered by means of a marking switch MS which hasfour marking wires and is positioned by a stepping magnet KB the windingof which is connected in series to the b-wiper of the register finderRZ. At the input the cord DS is connected with a call finder OZ and atthe output with a line selector LK. The winding of the stepping magnetKM of the line selector LK is energized in an electric circuit includinga contact controlled by a starting relay SR, which operates when thewanted number has been registered as more fully to be explainedhereinafter. The line selector LK starts and the wiper b thereof teststhe associated bank having four contacts. Four generators G G G and Gproduce four frequencies corresponding, respectively, to those of theband pass filters F F F F F F and R and F The stepping magnet KM of theline selector LK is released as soon as the test wiper thereof has foundthe filter F that passes the current with the frequency applied over themarking switch MS, in consequence whereof a D. C. relay TFR which isconnected to a rectifier arrangement R is energized by the rectifiedalternating current and interrupts by means of a contact controlled byrelay TFR the circuit of the stepping magnet KM of the line selector LK,so that this selector stops in the desired position, after which thetransmission of ringing tone, the switching through of the cord and thetermination of the operation of the register can be effected in theusual way.

In Fig. 1 the testing bank b of the line selector LK is connected withthe bank 12 of the call finder OZ so that the calling subscriber can beidentified by the register in the following manner: The wiper b of thecall finder OZ is connected to the bank a of the register finder RZ thewiper a of which is connected to one input terminal of a rectifierarrangement R the output of which is connected to an identificationrelay IR. The other input terminal of the rectifier R is connected tothe wiper of an identification switch IS. The four contacts in the bankof the identification switch IS are connected to the four generators G GG and G respectively.

Under the control of switching elements (not shown) with which theregister is equipped, the stepping magnet KA of the identificationswitch IS is energized, so that the wiper of the switch IS rotates untilthe same has found that frequency which is passed by band filter F andindicated by the position of the wiper b of the call finder OZ.

When the correct frequency is found, the relay IR is energized, afterwhich magnet KA is released by opening the contact of the relay IR. Theposition of the identification switch IS shows the number of the callingsubscriber. Double test can be avoided in the known manner, optionallyby means of application of an auxiliary direct current test. Theautomatic exchange: for four subscribers shown in Fig. 1 can be extendedto a decimal automatic exchange by enlarging the switches to decimalswitches, by increasing the number of frequencies to ten, and extendingthe number of filters l0 $61. t or p nding :o the various frequencies.

It is, however, not necessary to use ten different frequencies for adecimal automatic exchange according to the invention, since fourdifferent frequencies will sufiice, which, when used in combinations,can indicate maximally 16 different positions of the switching elements.

The principle of such an arrangement will be explained with reference toFig. 2, in which a decimal automatic exchange is shown making use ofcombinations of frequencies in order to characterize the variouspositions of the switching elements. The calling subscriber P lifts thehook or gives the starting criterion, and then receives the dialingtone.

A free cord DS and a free register are then connected to the subscriber,as explained with reference to Fig. l. The selected number consisting ofone digit, is registered by the marking switch MS, which is adjusted bythe stepping magnet KB as more fully described in connection with Fig.l, and can be converted by means of the four contact banks a-d of themarking switch MS into a combination of four frequencies.

In Fig. 2 the combinations of the frequencies are such that, if thesefrequencies are given the indices 1, 2, 4 and 8, respectively, the sumof the indices of the combination of frequencies indicated by aparticular position of the marking switch MS, is equal to the digittransmitted by the calling subscriber.

In many cases the marking switch can advantageously be replaced by arelay counting arrangement, which registers the digits as combinationsof the energization of four relays.

The testing bank b of the line selector LK has ten contacts the first ofwhich is connected to the filter F that passes the frequency ofgenerator G The second contact of the testing bank is connected to thefilter F that corresponds to the frequency of generator G the thirdcontact to the two filters F and F in parallel, passing the frequenciesof generators G and G the fourth contact to filter F (not shown) and soon up to the tenth contact which is connected to filters F and F inparallel. Conversions may be obtained by an unsysternatic mounting ofthe filters.

When the registering of the number of the called subscriber by themarking switch MS is finished, the register starts the line selector LK.The starting relay SR is energized in a way not shown in Fig. 2. Thecontact 2 of the starting relay SR closes the circuit of the steppingmagnet KM of the line selector LK. The contact 3 of the starting relaySR prepares a circuit for the test relay TFR. The contact 1 of thestarting relay SR applies the four frequencies to four rectifierarrangements, R R R R the outputs of which are connected to fourchecking relays TR TR TR,, and TRg, respectively. These relays eachcontrol one changeover contact. One combination of the operation ofrelays TR TR TR,, and TR is shown in Fig. 2, this combinationcorresponding to the number 6=4-{-2. The relays TR TR;,, TR, and TRg areenergized in every outlet of the line selector LK in accordance with thecombination of frequencies belonging to the particular position of thetesting wiper b of the line selector.

The four contact banks a, b, c and d of the marking switch MS and thechange-over contacts of the relays TR TR TR; and TR are so connected tothe remaining arrangement that e. g. in position 6 (=2+4) of the markingswitch MS a circuit is closed over the changeover contacts of the relaysTR TR T R; and TR and the contact banks ad of the marking switch MS ifthe relays TR and TR; are energized, thus completing a circuit for therelay TFR.

Therefore, it will be understood that if the test-wiper b of lineselector LK energizes the relays TR TR TR TR on a particular outlet inthe combination indicated by the position of the marking switch MS, therelay T PR is energized and the circuit of the stepping magnet KM of theline selector LK is interrupted. In this position the line selector LKhas reached the outlet to which the wanted subscriber is connected.After this the operation of the register can be finished in a known way.

The circuit for the identification of the calling subscriber operatesaccording to the same principle as the register circuits, with thedifference that during the identification the call finder OZ isstationary and the identification switch IS in the register moves, whilein the register circuit the marking switch MS is stationary. As in theautomatic exchange system according to Fig. 1, the generators and thefilters can change places, so that the testing multiple of the callfinders, group selectors and line selectors is permanently under tone.

Referring now to Figs. 3 and 4, the principle disclosed hereinabove withreference to Fig. l is applied to an automatic exchange servingsubscribers the numbers of which have three digits. The arrangement isonly shown insofar as it is necessary to explain the operation of theautomatic exchange.

When the calling subscribers hook (not shown) is lifted a circuit isclosed for the relay LB of the line circuit, the circuit running fromground over contact 3 of relay LB, contact 3 of relay LA, b-wire,subscribers loop (not shown), a-wire, contact 1 of relay LA, firstwinding of relay LB, battery, to ground. Relay LB attracts the armaturethereof and over the make position of contact 3 the slow releasing relayOZB is operated which starts the line finder OZ. The circuit for relayOZB leads from ground in the line circuit over front contact 3 of relayLB, contact 2 of relay LA, a multiple connected with relay OZB belongingto a seized group of line finders, battery, to ground. The relay OZBcloses an operating circuit for the stepping magnet KOZ of the linefinder OZ which starts hunting for the calling line. By means of theoff-normal contact ONC the b-wire is kept grounded.

When the calling line is reached a circuit is established over thec-wiper, relay LA of the line circuit and switching relay OZA of theline finder circuit being operated.

This circuit runs from ground in the line finder circuit over thecontact 2 of relay OZB, first and second wind ing of relay OZA, wiper cof the line finder OZ, contact 2 of relay LB, second winding of relayLB, winding of relay LA, battery, to ground. Let it be supposed that theshown line finder OZ reaches the calling line first. The stepping magnetKOZ is released by interrupting the operating circuit thereof at contact3 of relay OZA. Relay LA interrupts the circuit for the multiples ofrelay OZB by means of contact 2 so that the remaining line finders arestopped.

Relay OZA switches the aand b-wire to the register finder RZ by means ofcontacts 1 and 2, whereas the stepping magnet KOZ cannot be started byanother subscriber because the circuit thereof is interrupted at contact3 of relay OZA. Relay OZA holds itself over the second low ohmic windingand the contact 4 thereof. By means of contact 5 a circuit is preparedfor relay OZC.

A circuit is now closed for relay OZD from ground in the line circuit,over contact 3 of relay LA, bank and wiper b of the line finder OZ,contact 2 of relay OZA, contact 4 of relay DR, contact 3 of relay OZC,first winding of relay OZD, battery, to ground. Contact 1 of relay OZDcloses a holding circuit for relay OZA whereas over contact 2 of therelay OZD a circuit is closed for a slowly releasing relay RZB.

The register finder R2 is now operated by means of the stepping magnetKRZ thereof which is operated in a circuit from ground, over contact 3of relay RZA, contact 1 of relay RZB, magnet KRZ, battery, to ground.The energization of the stepping magnet KRZ is continued until thecalling line is found. At this moment relay OZC in the line findercircuit and relay RZA in the register are operated in the circuit:ground in the register, over contact 2 of relay RZB, first and secondwinding of relay RZA, wiper d of the register finder RZ, contact 5 ofrelay OZA, winding of relay OZC, battery, to

6 ground. The operating circuit for magnet KRZ in tk register isinterrupted at contact 3 of relay RZA so th: the register finder RZ isstopped on the calling line. Th impulse relay ISR in Fig. 4 is nowconnected to th calling subscriber over contacts 4 and 5 of relay RZ. inFig. 3 and wipers e and f of the register finder R2 A holding circuitover the low ohmic winding of rela RZA is established at the contact 2thereof. Contact of relay ISR shown in Fig. 3 closes a circuit for theslo releasing relay RZC.

The slow releasing relay OZC in the line finder circui is operated inthe operating circuit of the switching rela RZA in the register andinterrupts the circuit for rela OZD whereas contact 1 of the relay OZCcloses a hold ing circuit of relay OZA, thus taking over the part ccontact 1 of relay OZD. Relay OZC holds the cor and switches dialingtone to the calling subscriber wh now may start the selection.

When pulsing out the wanted digits relay ISR i the register in Fig. 4 isenergized in three series by th impulses. During the first series thecam X of a Si quence switch establishes a circuit for the stepping magnrKD of a first marking switch M5 during the secon series a circuit forthe stepping magnet KE of the secon marking switch M8 and during thethird series for th stepping magnet KF of the third marking switch M8 arestablished by the cam X. Thus the marking switche M8 M5 and M8 arepositioned by the stepping mag nets KD, KB and KP, respectively.

The sequence switch regulates also the positioning c the group selectorGK and the final selector LK b controlling over the cams A, B, C and Dthereof, th transmission of the different frequencies and the ope] ationof the associated stepping magnets and the steppin of the sequenceswitch.

During the first position cam D connects the mark ing switch MS with theregister finder RZ. The markin switch MS; has a bank of contacts markedby frequenc generators corresponding to the hundreds digits of thnumbers. Now a specific one of these frequencies sup plied by agenerator G and the associated filter F is applied over the markingswitch M8 cam D of th sequence switch, wiper h of the register finderRZ, bac contact 2 of relay 0R rectifier arrangement R th output of whichis connected to a test relay TFR t wiper d of group selector GK.

The relay KMR is energized in a circuit from groun in register, cam C ofsequence switch SR, wiper g c register finder RZ, back contact 1 ofrelay 0R back cor tact 1 of relay GT relay KMR battery, to grounc RelayKMR, attracts the armature thereof, thus th stepping magnet KM, of thegroup selector GK is er ergized in a circuit: ground, back contact ofrelay GTR; front contact of relay KMR stepping magnet KM bat cry, toground. Thus the group selector GK is starter When the wiper 0! thereofreaches a contact which i connected with the filter F passing thefrequency issue by generator G relay TFR is energized. If a free out letis found over the wiper c by a direct current tesrelay GTR is energizedin a circuit: ground, front cor tact of relay TFR relay GTR wiper c ofgroup selecto GK, test-relay TR, battery, to ground. This causes thattraction of the armature of relay GTR which break the circuit forstepping magnet KM so that the group se lector GK is stopped in thedesired position. Relay GT is now energized in a circuit: ground, frontcontact c relay GTR relay GT battery, to ground. Thus, holding circuitfor relay TR is formed over front cor tact 3 of GT relay GTR wiper c ofgroup selecto GK, relay TR, battery, to ground. With contact 1 rela GTbreaks the circuit for relay KMR thus causin starting relay SR in theregister to be released. Back con tact of SR now energizes the steppingmagnet RM 0 the sequence switch thus switching the next frequenccorresponding to the tens digit to wiper h of the registe inder RZ. Theemission of the frequency of the markng switch M8 is stopped and relayTFR is released, vhile via the back contact of relay TFR; and frontconact 2 of relay GT the switching relay R is energized, vhich by meansof the contacts 1 and 2 thereof switches he register through to afollowing stage (in this case the inal selector LK).

Relay SR is again energized in a circuit: ground, cam

relay SR, wiper g of the register finder RZ, front ontact 1 of relay 0Rback contact 1 of relay DR, viper a of the group selector GK, backcontact 1 of relay )R back contact 1 of relay GT2, back contact 1 ofrelay 3T relay KMR battery, to ground. Relay KMR tttracts the armaturethereof and thus closes a circuit for he stepping magnet KM from groundover back conact of relay GTR back contact of relay GTR front ontact ofrelay KMR stepping magnet KM battery, 0 ground. The final selector LK isstarted for positioning .ccording to the tens digit.

Simultaneously the frequency issued by generator G 9 applied to wiper eof the final selector LK in the circuit round, generator G filter Fmarking switch M am D of sequence switch, wiper h of the register findertZ, front contact 2 of relay 0R back contact 2 of clay DR, wiper b ofthe group selector GK, back conact 2 of relay DR back contact 2 of relayCR and the k. C. testing arrangement including rectifier arrangement Rand relay TFR to wiper e of the final selector .K.

When wiper e of the final selector LK reaches the conact in the levelconnected to the filter F which passes he frequency issued by generatorG relay TFR is ener- ;ized; thus relay GTR is energized in a circuit:ground, ront contact of relay TFR relay GTR battery, to wound. By theattraction of the armature thereof relay 3TR breaks the circuit for thestepping magnet KM hus stopping the final selector LK, and at the sametime :loses a circuit for relay GT running from ground over vack ofcontact of relay GTR front contact of relay ETR relay GT battery, toground.

Thus the circuit for relay SR in the register is interupted by thecontact of relay GT so that the stepping nagnet RM of the sequenceswitch is brought to the next losition thereof. Therefore the frequencyfrom gen- :rator G is no longer transmitted so that the relay TFR'eleases, thus causing relay 0R to be energized in a circuit rom groundover back contact of relay TFR front conact 2 of relay GT relay 0Rbattery, to ground. Thus he front contact 1 of relay 0R closes a holdingcircuit or relay 0R The release of relay TFR causes the elease of relayGTR by removing the ground, and thus .180 causes the deenergization ofthe relay GT Thereore, in order that relay 0R may be energized and formtholding circuit for itself, either relay GTR or relay GT must besufficiently slow in releasing.

With the contact 2 relay 0R switches the line, over vhich the frequencyis issued, through to the rectifier arrangement R test-relay TFR andwiper d of final elector LK. Relays SR and KMR are energized as beore,causing the re-energization of the stepping magnet (M Wiper d of thefinal selector LK now selects in the ens level determined by theposition of wiper e, the units ligit that corresponds to the frequencyemitted by gen- :rator Gr. When this has been done, relay TFR is:nergized, causing the energization of relay GTR which vith the contactthereof breaks the circuit for stepping nagnet KM thus stopping thefinal selector LK. Relay T is energized in a circuit: battery, windingof relay 3T front contact of relay GTR ground. The contact of relay GTbreaks the circuit for relay SR, thereby ndicating that the wantedoutlet has been found, so that he sequence switch is restored to normaland the register s disconnected. Relay GTR has formed a holding circuitaver front contact 3 of relay GT Now when the emission is stopped, relayTFR is tie-energized, thus closing a circuit for relay DR the circuitextending from ground over back contact of relay TFR front contact 2 ofrelay GT to relay DR battery, and ground. Relay DR connects by means ofa cord circuit (not shown) the calling subscriber with the called one.

The bottom part of Fig. 3 shows the identification register. Thecontacts of the banks 0! and e of the line finders OZ are connected by amultiple to ten filters E, and F respectively. The contact on whichwiper e is positioned indicates the units digit, and the contact onwhich wiper d is positioned indicates the tens digit. The hundreds digitwhich is not indicated by the call finder OZ, is indicated by theposition of wiper c of the register finder RZ.

First the stepping magnet KA of the identification switch 18 isenergized in a circuit: ground, interrupter contact RO, back contact IR,cam W of the sequence switch, stepping magnet KA, battery, to ground.

The identification switch 15 starts stepping and, over cams Z and Y ofthe sequence switch, the wiper of the identification switch 1S tracesthe band filter which passes the frequency corresponding to the unitdigit indicated by the position of wiper e of line finder OZ, which issupplied to the contact bank of identification switch 18 by 'a multipleof different generators G and filters F When this frequency is passedthe wiper of the identification switch IS; has reached a position inwhich the test relay IR is energized in a circuit: ground, generator Gband filter F identification switch 13 cam Z of the sequency switch,rectifier arrangement R and relay IR, cam Y of the sequence switch,wiper a of the register finder RZ, wiper e of line finder OZ, bandfilter F to ground.

Relay IR breaks the circuit for the stepping magnet KA, thus stoppingthe identification switch 15 in the desired position and simultaneouslygiving the sequence switch a stepping impulse by suitable means (notshown). The sequence switch now breaks the circuit for relay IR, whichreleases the armature thereof and closes a circuit for a stepping magnetKB of the identification switch 15 which now steps until the wiperthereof reaches the contact which corresponds with the tens digit, i.e., with the frequency which is passed by the band filter F generated bygenerator G, which corresponds to the position of the wiper d of theline finder OZ, thus energizing relay IR, which breaks the circuit forthe stepping magnet KB, and so stops the identification switch 18 whilethe sequence switch now breaks the circuit for relay IR and connects thestepping magnet KC with ground of the interrupter RO. Identificationswitch 1S now steps until the same reaches the position corresponding tothe frequency which is passed by the band filter corresponding to theposition of wiper c of register finder RZ; relay IR is then energizedand breaks the circuit for the stepping magnet KC, which stops theidentification switch 15 in the desired position.

The number of the calling subscriber is then indicated by the positionof the three identification switches 18 {S 18 switch 15 indicating thehundreds, switch 18 indicating the tens and switch IS; indicating theunits. The register receives three impulse series from the subscriber,which by means of the impulse relay ISR and the cam X of the sequenceswitch are transferred to the magnets KD, KB and KP of the three markingswitches M8 M5 and M5 respectively. Thus these three marking switchesare positioned according to the calling subscribers wish. After asufficient number of digits has been received the positioning of thegroup selector GK and the line finder LK commences.

If necessary the marking switches MS can serve assubscriber-identification-switches after the termination of theirpositioning functions. It is further remarked that in a local exchangeaccording to Figs. 3 and 4 only 10 receiving filters F and tengenerators G with ten transmission filters F have to be installed.According to the same principles as are applied in Fig. 3, the decimalautomatic exchange as explained with reference to Fig. 2, utilizingcombinations of testing frequencies, may be extended to larger systems.

The automatic telegraph or telephone system according to the inventioninvolves particular advantages when applied to trunk exchanges and theirproblems concern ing traflic handling. The local exchanges belonging toa system of trunk exchanges according to the invention may be equippedaccording to an arbitrary system.

Figs. 3, 5, 6, 7 and 8 show in priniciple the handling of the trunktrafiic between three exchanges A, B and C. The trunk group selectorssuch as GK, shown in Fig. in the exchange A, have outlets to exchangesnot shown and also outlets to the exchange B shown in Fig. 6 and to theexchange C shown in Figs. 7 and 8. The exchange B also has outlets tothe exchange C. In this system according to the invention it is possiblewithout the transmission of impulse series in case the bundle of linesbetween the two exchanges A and C is fully occupied, to lead the trafiicfrom the exchange A to C over the exchange B. The particular advantagethat no occupancies in the alternative route in the direction from theexchange A to exchange C over exchange B occur if there are free linesin the direct route from the exchange A to exchange C, is combined bythe system according to the invention with a rapid operation approachingthe speed of the direct system, since the positioning of the selectorsmay be carried out either in the alternative route or in the directroute. Therefore, the facility of a continuous or a limited continuoushunting facility inherent to the register systems can be utilized. Thiswill 'be explained by means of Figs. 3, 5, 6, 7 and 8. In the exchange Aa trunk group selector GK, is shown in Fig. 5, and a part of a register,which is connected to the group selector GK via a register finder R2,.The positioning of the register is explained with reference to thesystem of Figs. 3 and 4. It is supposed that the recording of one digitin this register is sufiicient to control the connected trunk groupselector 6K If necessary the register can be equipped for thepositioning of the group selector GK by more than one digit. It ispossible to include conversion-facilities in the automatic systemaccording to the invention, as it is the case with every registersystem. Considering that this fact is not part of the present invention,conversions are not included in the shown embodiments.

Let it be supposed that only one digit is necessary for routing, so thatrelay ISR pulses one digit to the marking switch MS Then a circuit isclosed from ground over the cam C of the sequence switch to the windingof the starting relay SR the loop over the wipers g and h of theregister finder RZ the back contacts of the switching relay OR,, themiddle of the first winding of a transformer TR the back contact 1 of arelay GT a relay KMR,, and battery to ground. Thus relay SR and relayKMR are energized which closes a circuit for the stepping magnet KM, ofgroup selector GK KM, is energized in a circuit: ground, back contact ofrelay GTR front contact of relay KMR stepping magnet KM battery, toground.

At the same time the two testing frequencies belonging to the numbers ofthe exchanges B and C are applied to the transformer TR by means of thecontacts of cam D of the sequence switch in the register; thefrequencies are generated, respectively, by the generators 6,, and 6,}in the circuits from ground, generators G, and 6 their associatedfilters P and F the wipers a and b of the marking switch MS which ispositioned by the mentioned impulse series, the rectifier arrangementsconnected to test relays AR and BR, cam D, primary winding oftransformer TR to ground. Over the secondary winding of the transformerTR the wipers g and h of the register finder R2,, the

back contacts of the relay 0R the transformer TR, and the rectifierarrangement connected to the testing relay TFR the two testingfrequencies are applied tc the wiper d of the group selector GK Thegroup selector should be provided with a home position, while thecontact bank should be mounted in such a way that the contacts of themain direction to exchange C lie in the bank before the contacts of thelines of the overflow to exchange B, so that the wiper d of the trunkgroup selector GK, first tests the contacts of the main direction andthe contacts of the overflow later only in case there are no free linesin the main direction.

If a free line is found in one of the two groups, the group selector GK,stops in a way which has been described with reference to Fig. 4, e. g.in the first selecting stage by means of relays TFR GTR GT KMR OR, andstepping magnet KM There should be a criterion in the register, whichindicates whether a free line is found in the main direction or in thealternative route. For, if a free line is obtained in the maindirection, the emission of the following digits in the form ofalternating currents of predetermined voice frequencies can take placenormally; if, however, a free line in the alternative route is obtained,a repetition of the call should be effected from exchange B.

In order to efiect this, the marking switch MS, oi the first digit hastwo banks a and b. When there is a call for exchange C, the testingfrequency of this exchange is applied to bank b of the marking switch M8while the testing frequency of the exchange B is applied to bank a ofsaid switch. By means of the relays AR and BR the register is informedin what group of lines the group selector GK finds a free outlet. Afterthe group selector GK, has found an outlet, the starting relay SR isreleased, since relay GT, is energized and thus breaks the circuits forrelays KMR, and SR Relay SR now releases the armature thereof and thusapplies ground to one of the contacts of cam B of the sequence switch,depending on whether relay AR or BR has been energized, thus controllingthe sequence switch.

If relay BR is energized, i. e. if a free line to exchange C has beenfound the sequence switch is directed in such a manner (not shown in thedrawing) that the frequency of the following digits recorded by theregister is emitted. If, however, relay AR had been energized, i. e.when a line in the alternative route had been obtained, then thesequence switch is directed to that position in which the frequencyapplied to bank b of the marking switch MS, is emitted again.

In both cases ground is applied to the loop of the wipers g and h of theregister finder RZ, over cam C of the sequence switch, as startingsignal for the apparatus in the next exchange. Depending on whether atwo-wire or four-wire trunk line is applied the starting-andswitchingthrough criterion can 'be passed on in usual manner.

For the sake of simplicity the drawings relate to a two-wire trunk fromwhich an arrangement for a fourwire trunk is easily deduced.

The frequency which is emitted in exchange A can position the apparatusin the other trunk exchanges only under special circumstances withoututilizing special switching elements, for instance if the testing wipersof two different selectors are directed to the same group of contacts,and if these wipers simultaneously move in another group which is notthe right one. In this case the same testing or control frequency isapplied to both the testing wipers. If these frequencies come fromdifferent exchanges, the phase is, as a rule, not the same, whichenables the energization of the two relays TFR of the moving selectorswhich test a free line in an undesired group of contacts.

This difiiculty can be overcome by synchronizing the generators andimparting a special phase rotation to the trunk lines between theexchanges, so that the various incoming control frequencies always havethe same phase as 1e frequencies present in the exchange. Another soluoncan be obtained by applying separate filters to the :lecting stagebelonging to a particular group of trunk nes. This causes, however,difliculties if the various roups have the same filters. A simplesolution, which satisfactory under any circumstances, and which can)mprise conversion facilities, which for some reason )uld not beprovided in the register of the exchange ssociated with the callingsubscriber, is the equipment of set of registers belonging to aparticular group of lines ith filters common to these registers, thefilters being at the same as those applied in the local exchange.

The group of lines in exchange B coming from exchange is provided withregisters, which can be connected to IE calling trunk line by means ofthe register finder RZg. he two shown incoming circuits of exchange Care uipped each with a register belonging to each line, which lay havevery small dimensions.

Let it be supposed that the group selector GK of exiange A has found afree outlet in the main direction to re exchange C. The start impulse isapplied as ground I earn C of the sequence switch in the register ofexiange A and extended over relay SR primary winding E transformer TRwipers g and h of register finder RZ 'ont contacts 1 and 2 of relay Rback contacts 1 nd 2 of relay DR wires a and b, leads 3 and 4 leadingver Fig. 6 to Fig. 7, back contacts of relay DR priiary winding oftransformer TR back contact 2 of relay relay R battery, back to ground.Relay R is now nergized, and a free register engaged in the direct routey means of the register finder RZ A free register is seized by operatingthe seizing relay MR in the circuit: ground over contact 2 of relay R alultiple of register seizing relays of which relay KMR shown, battery toground. The stepping magnet KM energized and the register finder R2tests over the 'iper b thereof for the calling line, which test whenfindlg said line, results in the operation of relay T and relay thecircuit being: ground, relay T contact 1 of :lay R wiper b of theregister finder RZ back contact f relay D relay C battery, ground.

The contact 2 of relay C interrupts the operating ciruit of the steppingmagnet KM of the register finder Z Relay T closes a holding circuit overthe contact 1 iereof and interrupts the circuit for relay R at contact 2frelay T Relay R releases and breaks the circuit for re- 1y KMR so thatthe register finder may not be started gain. A circuit is nowestablished for relay KR from round in Fig. 5 over cam C of the sequenceswitch of :gister A, relay SR mid point of secondary of trans- )rmer TRwipers g and h of register finder RZ front ontacts 1 and 2 of relay 0Rback contacts 1 and 2 f relay DR wipers a and b of the trunk groupselector 1K leads 3 and 4 in Fig. 6 to Fig. 7, contacts 1 and 2 of :layDR primary of transformer TR front contact 2 f relay T wiper d of theregister finder RZ front contct 4 of relay C back contact 1 of relay HSRrelay LR battery, to ground.

Relay KR attracts the armature thereof and thus closes 1e circuit:ground, back contact of relay 1R front conlCi'. of relay KR steppingmagnet KM battery to ground a that the stepping magnet KM of the markingswitch 18 is energized until the wiper a of marking switch M8 nds thefilter F corresponding with the frequency mitted by the generator G ofthe register in exchange A. hen the relay IR;; is energized in thecircuit: ground, lter F wiper a of marking switch M8 rectifier and re-1y 1R front contact 1 of relay C wiper a of register nder RZ transformerTR back contacts 1 and 2 of relay )R leads 3 and 4 in Fig. 6, wipers aand b of group sezctor GK back contacts 1 and 2 of relay DR frontconacts 1 and 2 of relay 0R wipers g and h of register finder 1Ztransformer TR cam D of sequence switch, rectifier nd relay AR, wiper aof marking switch M8 filter F generator G ground. By attracting thearmature there of, relay 1R interrupts the circuit of the steppingmagnet RM shown in Fig. 7, thus stopping the marking switch M8 Thissearching for the recorded frequency is analogous to the identificationof a subscriber in a local exchange. Thereafter the relay HSR closes atthe contact 3 thereof the circuit for the emission of the localfrequency corresponding to the frequency received from the exchange A.If necessary a systematical interchange of the control frequencies maybe applied at this point. In this manner the control or testingfrequency at the wipers of the various selecting stages has always thesame phase for the same frequencies. As a result of the energization ofrelay 1R relay SR and the relay KMR of the stepping magnet KM of thegroup selector GK in exchange C are energized. Relay SR is energized inthe circuit: ground, front contact of relay 1R relay SR wiper f ofregister finder RZ back contact 1 of relay 0R back contact 1 of relay GTrelay KMR battery, ground.

Relay KMR closes the circuit: ground, back contact of relay GTR frontcontact of relay KMR stepping magnet KM battery, ground.

The magnet KM is energized and the group selector GK; starts hunting.With the front contact 2 thereof relay SR; closes the circuit of theauxiliary starting relay HSR over: ground, front contact of relay 1Rfront contact 2 of relay SR relay HSR battery to ground. Front contact 3of relay HSR closes the circuit over which the frequency emitted bygenerator G is applied to bank b of the marking switch M8 The searchingand testing of a free outlet in the desired direction and the switchingthrough to the following selecting stages is efiected in the same manneras described with reference to Figs. 3 and 4. When a free outlet isfound, the armature 1 of relay GT interrupts the circuit of the relay SRRelay SR releases and interrupts with the armature 1 thereof thejunction of the register in exchange C with the register in exchange A,as a sign that the last-mentioned register can switch through to theemission of the frequency of the next digit. The emission of thealternating current of exchange A is interrupted, so that relay 1Rreleases the armature thereof which breaks the circuit of relay HSRwhich is deenergized. The following digits direct the followingselecting stages as long as these stages stay in exchange C.

The testing of a connection leaving exchange C may be indicated e. g. bythe finding of ground at the bank e of the group selector. Thiscriterion may, however, also be indicated in another manner, e. g. bymeans of an extra bank at the marking switch M8 The ground criterion atbank 2 of the group selector or further selecting stages in the exchangeC forms the sign of the termination of the operation of the associatedincoming register. Over make contact 2 of relay GT both the switchingrelays DR; and DR which may be combined to one relay, are energized soas to switch the wires 0 and b through and restore the register tonormal.

The group selector remains operated depending on seizing criteria, whichare well-known in the art and are not considered here. If no free linesfrom exchange A to exchange C are available, while some to exchange Bare free, the sequence switch in the register A in Fig. 5, controlled bythe relay AR, is brought in such a position that the calling frequencyof exchange C is emitted in the alternative direction to exchange B,this being the overflow route.

In Fig. 6 a group selector GK of exchange B is shown together with aregister and a register finder R2 which may be common to a plurality ofincoming lines from exchange A. One separate set of filters is requiredfor all the registers belonging to this direction.

The emission of the before-mentioned starting criterion by the registerin exchange A in Fig. 5 energizes the relay R in exchange B. In its turnthe relay R operates the relays such as relay KMR in all the registersbelonging to the multiple, so that the stepping magnets such as KM ofthe register finders of all free registers belonging to the multiple areenergized. A free register is then engaged in the way describedhereinbefore with reference to Fig. 7.

The actual operation of the register is analogous to the one describedbefore for exchange C. When a free line in the group from exchange B toexchange C is available, the operation of the register in exchange B isterminated, while the register in exchange A can proceed in the normalway with the emission of the frequencies belonging to the next digitsover the line which is found available in cooperation with the auxiliaryregister in exchange C (Fig. 8) or other distant exchanges (not shown.)

If necessary, in the trunk system according to the present inventionthere can be a choice between several kinds of lines of difierent routesby increasing the number of routing relays AR and BR in the system.Moreover, in the route for the overflow of the intermediate exchanges,if necessary several times in succession, there can be a choice betweena direct route or an alternative route; or between a group of maindirection lines, or a group of overflow lines.

Figs. 9 and 10 show this possibility for a group selector from anintermediate exchange.

This arrangement shows a trunk group selector with the associatedregister, over which the traffic of a particular exchange can bediverted, and which can make a choice between a direct route and analternative route. This is a facility which can easily be provided inregister systems, and which in the system according to the presentinvention is especially useful owing to the speed of operation.

The case can be represented by four exchanges; A shown in Figs. 3 and 5,B shown in Figs. 9 and 10, C shown in Figs. 7 and 8, and D shown inFigs. 11 and 12. A is a district exchange belonging to the groupexchange B, and D is a district exchange belonging to the group exchangeC.

The traffic between A and D is supposed to be so heavy at times that analternative route A--D is required. The traflic between B and D is alsosupported to require an overflow. To direct a call from exchange A toexchange D three routes are available, i. e. the direct route AD, thealternative route AB and direct route BD; and the route AB-C-D. Thechoice between the routes AD and AB-D is quite analogous to that in thearrangement explained with reference to exchanges A and C in Figs. 5, 6,7 and 8. The addition of the route A-BC-D to AB-D can be effected byequipping the register of exchange B in the way shown in Figs. 9 and 10.

The register finder RZ (Fig. is started and a free register is connectedwith the calling line as described for Fig. 7 when a group selector GKin Fig. 5 seizes a line to exchange B in Fig. 9 after which the markingswitch MS in Fig. 10 hunts for the recorded frequency in the waydescribed with reference to Fig. 7 for the register of exchange C. Themarking switch MS is equipped with four banks of contacts. The frequencyof the overflow B-C is applied to the bank b of the marking switch MS;the frequency of the direct route B-D is applied to the bank 0. Theassociated group selector should have a home position, in order toenable the hunting wiper to test the lines in the main direction beforeoccupying a free line in the overflow. The relays AR and BR in theregister in Fig. 10 indicate whether the direct route or the alternativeroute is seized. When a free line is found, the group selector isstopped in the described way, except that the relay DR is not energized,so that the transit register remains in the circuit, since relay HDR isdeenergized. If a free line in the direct route is seized, the operationof the transit register is 14 not terminated, before over thealternative route, that is in this case over exchange C, a free line toexchange D is found by the continued transmission of the callingfrequency of exchange C, which is applied to wiper c of marking switchMS. This is effected as follows: in Fig. 10 the relay AR is energizedand thus bridges with its front contact 1, front contact 1 of relay SRand the front contact 1 of relay HSR so that the circuit of relay SR inthe exchange A and that of relay KAR in the exchange B are notdisconnected.

As a result of this the register in the preceding exchange A cannotswitch through the armatures of the relays thereof so that the emissionof the following digit is prevented. When the group selector GK in theexchange B has found a free line in the alternative route, relay SR inthe associated register releases, as a result of which the relay ARR isenergized in the circuit: ground, back contact 2 of relay SR frontcontact 2 of relay AR, relay ARR, battery, and forms a holding circuitover front contact 2 of relay ARR, back contact 2 of relay D to ground.The relay ARR interrupts the emission of the frequency of the generator6 applied to the bank b of the marking switch MS. By this interruptionthe relay OR (Fig. 9), switches the testing frequency applied to bank cof the marking switch MS to the following exchange. The switchingthrough of the wires a and b by means of the relay DR when ground isfound by wiper e, does not take place, as the relay HDR in Fig. 9remains de-energized. The positioning of the group selector GK in thenext exchange C is effected in the manner already described. As soon asrelay SR (Fig. 10) is energized, relay BBR is also energized in thecircuit: ground, front contact 2 of relay SR front contact 4 of relayARR, relay BBR, to battery. Relay BBR forms a holding circuit overcontact 2 thereof: ground, back contact 2 of relay D front contact 2 ofrelay BBR, relay BBR, to battery. With its front contact 1 relay BBRprepares a circuit for relay BRR. When the group selector GK in the nextexchange C has found a tree line, relay SR (Fig. 10) releases thearmatures thereof once more, owing to which the relay BR andconsequently the relay BRR is energized in the circuit: ground, backcontact 2 of relay SR front contact of relay BR, relay BRR, to battery.Now the relay HDR is energized in the circuit: ground, back contact 5 ofrelay BRR, wiper g of register finder RZ relay HDR, battery, so that theoperation of the register in Fig. 10 is terminated by the operation ofthe switching relay DR which is now energized in the circuit: ground,wiper e of group selector GK front contact of relay HDR, front contact 2of relay GT relay DR to battery and ground. In case of the switching on,the relay D in the register of Fig. 10 operates and interrupts thecircuit of the testing relay C the register being released for othercalls. If at the positioning action of the group selector a free line inthe cross direction is seized, the relay BRR is energized directly,owing to which the operation of the register is terminated directly.

By unsystematical mounting of the generators with respect to the variousbanks (b and c) of the marking switch MS, all kinds of conversions canbe realized. For a decimal passing of digits e. g. a d-bank can be addedto the marking switch MS.

Under particular circumstances advantageous use can be made of groupfinders instead of group selectors in local as well as in trunkexchanges. Fig. 13 shows the principle of a group finder in a telegraphor telephone system according to the invention. The system according tothe invention involves a specific advantage over the group selectorstages applied in known register systems. That is to say in the knownregister systems the register controls a positioning circuit with amarking switch by means of an impulse series. Only thereafter

